Add XdgOutputV1 version 2

Summary:
Will be useful for making plasma widgets not move about
on multi monitor. QtWayland already supports it

Test Plan: Unit test

Reviewers: KWin, zzag

Reviewed By: KWin, zzag

Subscribers: apol, kde-frameworks-devel

Tags: Frameworks

Differential Revision: https://phabricator.kde.org/D27535